Multi-cylinder internal combustion engine and method for operating such a multi-cylinder internal combustion engine

Abstract

A linearly aligned four-cylinder internal combustion engine system operated in a 1-3-4-2 sequence, comprising a cylinder head connected with a cylinder block wherein each cylinder has at least one exhaust port to discharge exhaust gasses via an exhaust gas discharge system, for which an exhaust gas pipe is connected at each exhaust port; wherein the exhaust gas pipes of the cylinders that merge in stages into a common exhaust gas pipe and the exhaust gas discharge system emerges outside of the cylinder head. Thus exhaust gas from consecutive ignitions in adjacent cylinders is separated for a distance throughout the engine head to reduce mutual influencing in adjacent cylinders with consecutive ignitions.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]The present application claims priority to German Application 102012200014.3, filed on Jan. 2, 2012, the entire contents of which are hereby incorporated by reference for all purposes.BACKGROUND AND SUMMARY[0002]The multi-cylinder internal combustion engines of motor vehicles often include at least one cylinder head connected to the mounting face of a cylinder block and four cylinders arranged in line along the longitudinal axis of the cylinder head, wherein each cylinder is equipped with ignition devices to initiate external ignition. Each cylinder generally contains at least one exhaust port to discharge the exhaust gasses from the cylinder via the exhaust gas discharge system, wherein each exhaust gas pipe is connected at each exhaust port. In the context of the following specification the term “engine,” in particular, comprises petrol engines equipped with external ignition. Engines have at least one cylinder head and one cylinder blo...

AI Technical Summary

Benefits of technology

The patent text addresses a problem in combustion engines where shortened exhaust pipes can cause mutual influence between adjacent cylinders, leading to power disadvantages at high speeds and reduced pumping in low load operation. The inventors provide a solution by isolating the exhaust pipes of adjacent cylinders to minimize the impact on charge change. The technical effect of this patent is the alleviation of mutual influence between cylinders while maintaining the benefits of a large valve overlap and a long exhaust opening duration.

Problems solved by technology

Lower loads rely upon a higher choking, so charge change losses are increased the low load region.

During valve overlap at high loads “flushing losses” can occur, wherein part of the aspirated fresh air flows through the cylinder without participating in the subsequent combustion.

Charge change has proved problematic for the exhaust pipes of the cylinders.

Short exhaust pipes can lead to a mutual disadvantage of the cylinders of the engine on the effect on charge change, in particular, the effect achieved by residual gas flushing may be decreased.

Thus in an in-line engine operated in a combustion sequence, the charge change of a cylinder can have a disadvantageous effect on the cylinder immediately preceding it in the ignition sequence due to different mechanisms competing to evacuate exhaust gas.

Use of large valve overlap is often heightened at low engine speeds by opening the valve later while maintaining closing time, this measure maintains engine torque at low engine rotation speeds; however, power disadvantages arise from shortened valve duration at high engine rotation speeds from the reduction in pumping in the low load range to reduce fuel consumption.

Images